The semiconductor industry has experienced technological advances that have permitted increases in density and/or complexity of semiconductor memory devices. Also, the technological advances have allowed decreases in power consumption and package sizes of various types of semiconductor memory devices. There is a continuing trend to employ and/or fabricate advanced semiconductor memory devices using techniques, materials, and devices that improve performance, reduce leakage current, and enhance overall scaling. Silicon-on-insulator (SOI) and bulk substrates are examples of materials that may be used to fabricate such semiconductor memory devices. Such semiconductor memory devices may include, for example, partially depleted (PD) devices, fully depleted (FD) devices, multiple gate devices (for example, double, triple, or surrounding gate), and Fin-FET devices.
A semiconductor memory device may include a memory cell having a memory transistor with an electrically floating body region wherein electrical charges may be stored. When excess majority electrical charge carriers are stored in the electrically floating body region, the memory cell may store a logic high (e.g., binary “1” data state). When the electrical floating body region is depleted of majority electrical charge carriers, the memory cell may store a logic low (e.g., binary “0” data state). Also, a semiconductor memory device may be fabricated on silicon-on-insulator (SOI) substrates or bulk substrates (e.g., enabling body isolation). For example, a semiconductor memory device may be fabricated as a three-dimensional (3-D) device (e.g., multiple gate devices, Fin-FETs, recessed gates and pillars).
In one conventional technique, the memory cell of the semiconductor memory device may be read by applying bias signals to a source/drain region and/or a gate of the memory transistor. As such, a conventional reading technique may involve sensing an amount of current provided/generated by/in the electrically floating body region of the memory cell in response to the application of the source/drain region and/or gate bias signals to determine a data state stored in the memory cell. For example, the memory cell may have two or more different current states corresponding to two or more different logical states (e.g., two different current conditions/states corresponding to two different logic states: a binary “0” data state and a binary “1” data state).
In another conventional technique, the memory cell of the semiconductor memory device may be written to by applying bias signals to the source/drain region(s) and/or the gate of the memory transistor. As such, a conventional writing technique may result in an increase/decrease of majority charge carriers in the electrically floating body region of the memory cell which, in turn, may determine the data state of the memory cell. An increase of majority charge carriers in the electrically floating body region may result from impact ionization, band-to-band tunneling (gate-induced drain leakage “GIDL”), or direct injection. A decrease of majority charge carriers in the electrically floating body region may result from charge carriers being removed via drain region charge carrier removal, source region charge carrier removal, or drain and source region charge carrier removal, for example, using back gate pulsing.
Often, a conventional semiconductor memory cell requires relatively large area and/or large power consumption when performing reading and/or writing operations. For example, a conventional semiconductor memory cell may be fabricated having various regions in a planar orientation and occupying a large area on a silicon-on-insulator (SOI) substrate or bulk substrate. Thus, a conventional semiconductor memory cell may have inefficient scalability and lead to an increase in the size of the semiconductor memory cell. Also, pulsing between positive and negative gate biases during read and/or write operations may result in an increase in power consumption of the conventional semiconductor memory cell.
In view of the foregoing, it may be understood that there may be significant problems and shortcomings associated with conventional floating body semiconductor memory devices.